Crystalline Beta-Lactamase Inhibitor

ABSTRACT

A crystalline compound of formula (I): 
     
       
         
         
             
             
         
       
     
     The compound of formula (I) is a β-lactamase inhibitor and may be administered in combination with an antibacterial agent for prevention or treatment of bacterial infection.

FIELD OF THE INVENTION

The present invention relates to crystalline (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide, processes for the preparation thereof, pharmaceutical compositions comprising (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide and uses of the compound, including uses of compositions containing the compound, in particular use with an antibacterial agent in treatment or prevention of bacterial infection.

BACKGROUND OF THE INVENTION

Emergence and dissemination of resistance is an inevitable consequence of the evolutionary dynamic set in motion by the introduction of antibiotics, irrespective of structural class or mode of action (Shapiro S. 2013. Speculative strategies for new antibacterials: all roads should not lead to Rome. J. Antibiot. 66: 371-386). Spread of resistance amongst clinically relevant pathogens has had an especially strong impact on the value of β-lactam antibiotics, heretofore regarded as very safe and efficacious therapies for serious bacterial infections. The appearance of new and aggressive β-lactamases, particularly extended spectrum β-lactamases (ESBLs) and other class A enzymes, has compromised the ability of β-lactams to combat infections, highlighting the need for development of new products (Fisher J F, Meroueh S O, Mobashery S. 2005. Bacterial resistance to β-lactam antibiotics: compelling opportunism, compelling opportunity. Chem. Rev. 105: 395-424). Whilst several β-lactamase inhibitors, which protect β-lactam antibiotics from hydrolysis, have been used in combination with some β-lactams, the capability of these β-lactamase inhibitors to preserve the antibacterial activity of β-lactams has eroded severely during the past decade, necessitating the search for new, more potent β-lactamase inhibitors to restore therapeutic utility of their β-lactam partners (Watkins R R, Papp-Wallace K M, Drawz S M, Bonomo R A. 2013. Novel β-lactamase inhibitors: a therapeutic hope against the scourge of multidrug resistance. Front. Microbiol. 4: 392).

WO 2008/010048 discloses the β-lactamase inhibitor (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide (formula I):

WO 2008/010048 discloses formation of an amorphous compound of Formula (I) which is isolated by filtering and lyophilisation.

The present inventors have found that the compound of formula (I) as prepared by the process of WO 2008/010048 is hygroscopic, and has limited stability when stored at room temperature.

It is an object of the invention to provide a more stable form of the compound of formula (I).

It is a further object of the invention to provide a form of the compound of formula (I) that is easy to purify.

It is a further object of the invention to provide a form of the compound of formula (I) that is easy to handle.

SUMMARY OF THE INVENTION

The present inventors have developed crystalline compounds of formula (I). The present inventors have surprisingly found that crystalline compounds of formula (I) have improved thermal stability, are less hygroscopic and easier to purify and handle than the compound of formula (I) in amorphous form.

In a first aspect the invention provides a crystalline compound of formula (I):

In a first embodiment of the first aspect there is provided a crystalline compound of formula (I, hereinafter “Form A”, characterised by an XRPD spectrum comprising four or more (preferably five or more, preferably six or more, preferably seven or more, preferably eight or more, preferably nine or more, preferably all ten) peaks selected from peaks with 2θ angles of: 8.82, 12.07, 14.43, 14.92, 16.26, 18.25, 19.06, 19.78, 20.82 and 23.51±0.1 degrees 2θ, optionally ±0.05 degrees 2θ.

Preferably, the XRPD spectrum of Form A has one, two, three, four or all five peaks selected from peaks with 2θ angles of: 8.82, 12.07, 14.43, 18.25 and 19.78±0.1 degrees 2θ.

Preferably, the XRPD spectrum of Form A has all ten peaks with 2θ angles of: 8.82, 12.07, 14.43, 14.92, 16.26, 18.25, 19.06, 19.78, 20.82 and 23.51±0.1 degrees 2θ, optionally ±0.05 degrees 2θ.

Preferably, Form A has a XRPD spectrum substantially as shown in FIG. 1.

Form A may be further characterised by its Thermo Gravimetric Analysis (TGA) curve showing an endothermic event at about 163° C.±2° C. The TGA curve may show a weight loss of about 6% up to 130° C.±2° C. due to water loss.

Preferably, Form A has a TGA curve substantially as shown in FIG. 9.

Form A may be further characterized by its differential scanning calorimetry (DSC) curve showing an endothermic event with a maximum at about 163° C.±2° C. The DSC curve may show an endothermic event starting at about 45° C.±2° C. due to water loss.

Preferably, Form A has a DSC curve substantially as shown in FIG. 5.

In a second embodiment of the first aspect there is provided a crystalline compound of formula (I), hereinafter “Form B”, characterised by an XRPD spectrum comprising four or more (preferably five or more, preferably six or more, preferably seven or more, preferably eight or more, preferably nine or more, preferably all ten) peaks selected from peaks with 2θ angles of: 9.37, 10.34, 12.59, 13.17, 15.00, 15.63, 18.51, 19.10, 20.79, 23.93±0.1 degrees 2θ, optionally ±0.05 degrees 2θ.

Preferably, the XRPD spectrum of Form B has one, two, three, four or all five peaks selected from peaks with 2θ angles of: 10.34, 15.00, 15.63, 18.51 and 23.93±0.1 degrees 2θ.

Preferably, the XRPD spectrum of Form B has all ten peaks with 2θ angles of: 9.37, 10.34, 12.59, 13.17, 15.00, 15.63, 18.51, 19.10, 20.79 and 23.93±0.1 degrees 2θ, optionally ±0.05 degrees 2θ.

Preferably, Form B has a XRPD spectrum substantially as shown in FIG. 2.

Form B may be further characterised by its Thermo Gravimetric Analysis (TGA) curve showing an endothermic event at about 155° C.±2° C.

The TGA curve may show a weight loss of about 8% up to 120° C.±2° C. correlated with water desorption.

Preferably, Form B has a TGA curve substantially as shown in FIG. 10.

Form B may be further characterized by its differential scanning calorimetry (DSC) curve showing an endothermic event with a maximum at about 180° C.±2° C. The DSC curve may show an endothermic event starting at about 50° C.±2° C. due to water loss.

Preferably, Form B has a DSC curve substantially as shown in FIG. 6.

In a third embodiment of the first aspect there is provided a crystalline compound of formula (I), hereinafter “Form C”, characterised by an XRPD spectrum comprising four or more (preferably five or more, preferably six or more, preferably seven or more, preferably eight or more, preferably nine or more, preferably all ten) peaks selected from peaks with 2θ angles of: 9.33, 10.73, 14.85, 15.29, 15.77, 16.16, 18.60, 20.12, 21.00 and 23.22±0.1 degrees 2θ, optionally ±0.05 degrees 2θ.

Preferably, the XRPD spectrum of Form C has one, two, three, four or all five peaks selected from peaks with 2θ angles of: 10.73, 14.85, 15.29, 20.12 and 23.22±0.1 degrees 2θ.

Preferably, the XRPD spectrum of Form C has all ten peaks with 2θ angles of: 9.33, 10.73, 14.85, 15.29, 15.77, 16.16, 18.60, 20.12, 21.00 and 23.22±0.1 degrees 2θ, optionally ±0.05 degrees 2θ.

Preferably, Form C has a XRPD spectrum substantially as shown in FIG. 3 or FIG. 20.

Form C may be further characterised by its Thermo Gravimetric Analysis (TGA) curve showing an endothermic event at about 149° C.

The TGA curve may show a weight loss of about 3% up to 120° C.±2° C. correlated with water desorption.

Preferably, Form C has a TGA curve substantially as shown in FIG. 11.

Form C may be further characterized by its differential scanning calorimetry (DSC) curve showing an endothermic event with a maximum at about 185° C.±2° C.

Preferably, Form C has a DSC curve substantially as shown in FIG. 7.

In a fourth embodiment of the first aspect there is provided a crystalline compound of formula (I), hereinafter “Form D”, characterised by an XRPD spectrum comprising four or more peaks (preferably five or more, preferably six or more, preferably seven or more, preferably eight or more, preferably nine or more, preferably all ten peaks) selected from peaks with 2θ angles of: 6.78, 15.45, 16.39, 17.10, 20.06, 20.63, 23.23, 23.68, 26.18 and 32.47±0.05 degrees 2θ.

Preferably, the XRPD spectrum of Form D has one, two, three, four or all five peaks selected from peaks with 2θ angles of: 6.78, 16.39, 17.10, 20.63 and 23.23, ±0.05 degrees 2θ.

Preferably, the XRPD spectrum of Form D has all ten peaks with 2θ angles of 6.78, 15.45, 16.39, 17.10, 20.06, 20.63, 23.23, 23.68, 26.18 and 32.47±0.05 degrees 2θ.

Preferably, Form D has an XRPD spectrum substantially as shown in FIG. 25.

In a fifth embodiment of the first aspect there is provided a crystalline compound of formula (I), hereinafter “Form E”, characterised by an XRPD spectrum comprising four or more peaks (preferably five or more, preferably six or more, preferably seven or more, preferably eight or more, preferably nine or more, preferably all ten peaks) selected from peaks with 2θ angles of: 6.82, 15.04, 15.68, 16.47, 17.17, 18.44, 20.69, 23.34, 23.88 and 25.38±0.05 degrees 2θ.

Preferably, the XRPD spectrum of Form E has one, two, three, four or all five peaks selected from peaks with 2θ angles of: 15.04, 15.68, 16.47, 20.69 and 23.88±0.05 degrees 2θ.

Preferably, the XRPD spectrum of Form E has all ten peaks with 2θ angles of: 6.82, 15.04, 15.68, 16.47, 17.17, 18.44, 20.69, 23.34, 23.88 and 25.38±0.05 degrees 2θ.

Preferably, Form E has an XRPD spectrum substantially as shown in FIG. 27.

In a sixth embodiment of the first aspect there is provided a crystalline compound of formula (I), hereinafter “Form F”, characterised by an XRPD spectrum comprising four or more peaks (preferably five or more, preferably six or more, preferably seven or more, preferably eight or more, preferably nine or more, preferably ten or more, preferably all eleven peaks) selected from peaks with 2θ angles of: 12.73, 15.36, 15.95, 16.42, 18.12, 20.48, 22.85, 23.22, 27.04, 27.69 and 32.47±0.05 degrees 2θ.

Preferably, the XRPD spectrum of Form F has one, two, three, four or all five peaks selected from peaks with 2θ angles of: 12.73, 15.36, 15.95, 16.42 and 20.48±0.5 degrees 2θ.

Preferably, the XRPD spectrum of Form F has all eleven peaks with 2θ angles of: 12.73, 15.36, 15.95, 16.42, 18.12, 20.48, 22.85, 23.22, 27.04, 27.69 and 32.47±0.05 degrees 2θ.

Preferably, Form F has an XRPD spectrum substantially as shown in FIG. 29.

In a second aspect the invention provides a process for preparing crystalline compound of formula (I):

the process comprising the steps of: forming a formulation by dissolving or suspending an amorphous compound of formula (I) in a solvent or solvent mixture; and crystallising the compound of formula (I) from the formulation.

The amorphous compound of formula (I) in the formulation may substantially all be dissolved in the formulation; may substantially all be dispersed in the formulation; or may partly be dissolved and partly dispersed in the formulation.

The quantity of the amorphous compound of formula (I) used in the process of the second aspect of the invention may be below a solubility limit of the amorphous compound in the solvent or solvent mixture, in which case the formulation is a solution, or may be above the solubility limit, in which case the formulation is a suspension.

Solvents for dissolving the amorphous compound of formula (I) may be selected from solvents in which the amorphous compound of formula (I) has a solubility at 20° C. of greater than 200 mg/ml, optionally greater than 400 mg/ml. Solvents may be polar, protic or dipolar aprotic solvents. Exemplary polar, protic solvents are water, primary alcohols, preferably methanol, ethanol and 1-propanol. Further exemplary dipolar aprotic solvents are dimethylsulfoxide and N,N-dimethylformamide, N-methylpyrrolidone and the alike. Primary alcohols are preferred. Methanol and ethanol are particularly preferred. Water content of a primary alcohol solvent is preferably less than 4 wt %, more preferably less than 2 wt %. When the primary alcohol is methanol the water content is preferably less than 1%.

Crystallisation of a crystalline compound of formula (I) may be induced by adding an antisolvent to a formulation containing dissolved amorphous compound of formula (I). Antisolvents may be solvents in which the amorphous compound of formula (I) has a solubility at 20° C. of less than 50 mg/ml, optionally less than 30 mg/ml.

Antisolvents may be aprotic materials. Exemplary antisolvents are acetone, ethyl acetate, methyl-tert-butyl ether, heptane, 2-propanol, isopropyl acetate, diisopropyl ether, methylethyl ketone, tetrahydrofuran, anisole, and tert-butyl acetate.

In another embodiment of the second aspect, the amorphous compound of formula (I) may have little or no solubility in the solvent or solvent mixture used to form the formulation, in which case the formulation is a suspension.

A nucleating agent may be added to the formulation. The nucleating agent may be a crystalline seed of a compound of formula (I).

The purity of the solvent may affect solubility of the compound of formula (I) in the solvent, either in its amorphous form or in one or more of its crystalline forms.

The temperature of the formulation may be lowered following formation of the formulation. The solvent or solvent mixture may be heated during formation of the formulation, and may be cooled following formation of the formulation.

In a third aspect the invention provides crystalline compounds of formula (I) prepared by a process according to the second aspect of the invention.

The invention further provides crystalline compounds of formula (I) preparable by a process according to the second aspect of the invention.

For pharmaceuticals in which the active ingredient can exist in more than one polymorphic form, problems in dissolution and/or bioavailability of pharmaceutical compositions containing the compound can result if the manufacturing process leads to a polymorph with varying degrees of polymorphic purity and/or where the process does not control polymorphic interconversion.

If crystalline forms are made with polymorphic impurities, this may cause instability and it can accelerate significant interconversion to another polymorphic form. Therefore it is advantageous to produce crystalline forms with high polymorphic purity.

Preferably the crystalline compound of formula (I) according to the first or third aspects of the invention comprises more than 90% of a single crystalline polymorph of the compound, preferably more than 95%, more preferably more than 99%, even more preferably more than 99.5% and most preferably more than 99.8% as measured by XRPD or DSC, preferably as measured by XRPD. Preferably, the single polymorph is one of Form A, Form B, Form C, Form D, Form E, and Form F.

Preferably, the crystalline compound of formula (I) according to the first or third aspects of the present invention has a chemical purity of at least 95 wt %, more preferably at least 98%, more preferably at least 99%, more preferably at least 99.5%, even more preferably at least 99.8%, and most preferably at least 99.9%, preferably as measured by HPLC.

The crystalline compound of formula (I) may be suitable for reconstitution with a pharmaceutically acceptable vehicle for administration.

In a fourth aspect of the present invention there is provided a pharmaceutical composition comprising an antibiotic and the crystalline compound of formula (I) according to the first or third aspects of the present invention. Preferably, the pharmaceutical composition further comprises one or more pharmaceutically acceptable excipients.

In a fifth aspect the invention provides a pharmaceutical composition according to the fourth aspect for treatment of bacterial infection.

In a sixth aspect the invention provides a method of treating a bacterial infection comprising administering to a patient in need thereof a therapeutically effective amount of the pharmaceutical composition according to the fourth aspect of the present invention.

In a seventh aspect the invention provides a method of forming a pharmaceutical composition comprising a compound of formula (I), the method comprising the step of dissolving or dispersing the crystalline compound of formula (I) in a carrier liquid. Optionally the carrier liquid is a pharmaceutically acceptable vehicle for intravenous injections such as Dextrose, Sodium chloride & Dextrose 5 mixture. Sodium chloride, Sodium lactate, etc. Optionally, the carrier liquid is an aqueous saline solution.

The concentration of a compound of formula (I) in the pharmaceutical composition range from 1 mg/ml to 700 mg/ml, preferably from 100 to 500 mg/ml, more preferably from 150 to 250 mg/ml.

DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to the Figures in which:

FIG. 1 is a X-ray powder diffraction pattern of Form A of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide;

FIG. 2 is a X-ray powder diffraction pattern of Form B of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide;

FIG. 3 is a X-ray powder diffraction pattern of Form C of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide;

FIG. 4 is a X-ray powder diffraction pattern of amorphous form of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide;

FIG. 5 is a differential scanning calorimetric thermogram of Form A of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide;

FIG. 6 is a differential scanning calorimetric thermogram of Form B of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide;

FIG. 7 is a differential scanning calorimetric thermogram of Form C of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide;

FIG. 8 is a differential scanning calorimetric thermogram of amorphous form of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide;

FIG. 9 is a thermogravimetric curve of Form A of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide;

FIG. 10 is a thermogravimetric curve of Form B of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide;

FIG. 11 is a thermogravimetric curve of Form C of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide;

FIG. 12 is a plot of HPLC response area vs. concentration for solutions or suspensions of amorphous (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide;

FIG. 13 is a 25× magnified optical microscope image of Form A of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide;

FIG. 14 is a 25× magnified optical microscope image of Form B of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide;

FIG. 15 is a 25× magnified optical microscope image of Form C of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide.

FIG. 16 is a Raman spectrum of Form A of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide.

FIG. 17 is a FT-RT spectrum of Form A of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide.

FIG. 18 is a Raman spectrum of Form C of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide.

FIG. 19 is a FT-RT spectrum of Form C of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide.

FIG. 20 is a X-ray powder diffraction pattern of Form C of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide, obtained according to Example 13;

FIG. 21 is a thermogravimetric curve of Form C of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide, obtained according to Example 13;

FIG. 22 is a 25× magnified optical microscope image of Form C of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide, obtained according to Example 13;

FIG. 23 is an ¹H-NMR spectrum of Form C of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide.

FIG. 24 shows particle size distribution curves of Form C of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide, obtained according to Example 13;

FIG. 25 is a X-ray powder diffraction pattern of Form D of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide;

FIG. 26 is a Raman spectrum of Form D of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide.

FIG. 27 is a X-ray powder diffraction pattern of Form E of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide;

FIG. 28 is a Raman spectrum of Form E of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide.

FIG. 29 is a X-ray powder diffraction pattern of Form F of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide;

FIGS. 30 and 31 are Raman spectra of three bathes of Form F of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide.

FIGS. 32-39 are scanning electron microscopy images of samples of a first batch of Form F of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide;

FIGS. 40-46 are scanning electron microscopy images of samples of a second batch of Form F of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide;

FIGS. 47-50 are scanning electron microscopy images of samples of a third batch of Form F of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide;

FIG. 51 is a FT-RT spectrum of Form F of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide.

FIG. 52 is a differential scanning calorimetric thermogram of Form F of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide;

FIG. 53 is a thermogravimetric curve of Form F of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide;

FIG. 54 is a gas evolution image of Evolved Gas Analysis (EGA) of Form F of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide;

FIG. 55 is a plot of Dynamic Vapor Sorption (DVS) change in mass of Form F of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide; and

FIG. 56 shows Dynamic Vapor Sorption (DVS) isotherm plots of Form F of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides crystalline (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide which is non-hygroscopic, thermally stable and has beneficial properties that avoid problems associated with the prior art forms.

The present invention further provides a process for forming crystalline (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide. The process allows formation of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide in high polymorphic purity.

Suitable crystallization techniques for forming crystalline compounds of formula (I) include, without limitation, precipitation and re-crystallization (including antisolvent crystallization) processes, with or without seeding with nucleating agents. In a preferred embodiment, antisolvent crystallization processes are used.

Diluted, saturated or super-saturated solutions may be used for crystallization.

A solution of an amorphous compound of formula (I) may be cooled to promote crystallization of crystalline compounds of formula (I).

An amorphous compound of formula (I) may be dissolved at a temperature in the range of 20-50° C. The solution may be cooled down to about 0° C. or about 10° C. to promote the crystallization.

Methods of preparing crystalline forms of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide, include, without limitation, the following methods:

Form A Method 1:

-   -   stirring a solution of amorphous compound of formula (I) in         ethanol 96% at 20° C.,     -   collecting the solid by filtration.

Form A Method 2:

-   -   stirring a saturated solution of amorphous compound of         formula (I) in ethanol 96% at 20° C.,     -   adding methyl tert-butyl ether as antisolvent,     -   stirring the mixture at room temperature overnight,     -   collecting the solid by filtration.

Form A Method 3:

-   -   stirring a saturated solution of amorphous compound of         formula (I) in ethanol 96% at 20° C.,     -   seeding with nucleating agent,     -   adding heptane as antisolvent,     -   stirring the mixture at room temperature overnight,     -   collecting the solid by filtration.

Form A Method 4

-   -   stirring a saturated solution of amorphous compound of         formula (I) in ethanol 96% at 20° C.,     -   seeding with nucleating agent,     -   adding 2-propanol as antisolvent,     -   stirring the mixture at room temperature overnight,     -   collecting the solid by filtration.

Form A Method 5

-   -   dissolving amorphous compound of formula (I) in ethanol 96% by         heating to 35° C.     -   slowly adding (time: about 1 hour) methyl tert-butyl ether as         antisolvent,     -   cooling the mixture to 10° C.     -   stirring the mixture at 10° C. overnight,     -   collecting the solid by filtration.

Form A Method 6

-   -   stirring a saturated solution of amorphous compound of         formula (I) in ethanol 96% at 35° C.,     -   seeding the solution with nucleating agent,     -   slowly adding (time: about 20 min.) methyl tert-butyl ether as         antisolvent at 20° C.,     -   cooling the mixture to 20° C. overnight,     -   collecting the solid by filtration

Form A Method 7

-   -   stirring a saturated solution of amorphous compound of         formula (I) in ethanol 96% at 40° C.,     -   seeding the solution with nucleating agent,     -   cooling the mixture to 20° C. over about 5 hours,     -   stirring the mixture at 20° C.,     -   collecting the solid by filtration

Form B Method 1

-   -   stirring a saturated solution of amorphous compound of         formula (I) in acetone at 40° C.,     -   collecting the solid by filtration.

Form C Method 1

-   -   stirring a solution of amorphous compound of formula (I) in         ethanol 99.8% at 40° C.,     -   seeding the solution with nucleating agent at 36° C.     -   cooling the solution at 15° C.,     -   stirring the mixture overnight

Forms D, E and F may be formed by crystallization from dimethylformamide solution. The present inventors have found that Forms D and E may crystallize initially from DMF solution but do not form once form F has formed. Without wishing to be bound by any theory, this may be due to Form F having greater stability than either Form D or Form E.

Surprisingly, the present inventors have found that one crystal form of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide can be used to form another crystal form of this compound. One of crystal forms A, B and C may be used as a seed in crystallisation of another of forms A, B and C.

A pharmaceutical composition as described herein may be in an injectable form for intravenous injection. The composition may contain stabilizing agents. The composition may be in suitable sterile solid form ready for reconstitution to form an injectable solution.

A pharmaceutical composition containing a crystalline compound of formula (I) as described herein may be administered either alone or may be co-administered with therapeutically effective amount of an antibiotic.

A pharmaceutical composition as described herein may comprise an antibiotic and may comprise one or more conventional pharmaceutically acceptable excipient(s).

Exemplary antibiotics are β-lactam antibiotics, in particular penicillins and cephalosporins and may be selected from Amoxicillin, Ampicillin, Apalcillin, Azlocillin, Bacampicillin, Carbenacillin, Cloxacillin, Dicloxacillin, Flucloxacillin, Lenampicillin, Mecillinam, Methacillin, Mezlocillin, Nafcillin, Oxacillin, Penicillin G, Penicillin V, Piperacillin, Temocillin, Ticarcillin, Aztreonam, BAL30072, Carumonam, PTX2416, Tigemonam, Cefaclor, Cefadroxil, Cefalexin, Cefalotin, Cefamandole, Cefapirin, Cefazolin, Cefbuperazone, Cefdinir, Cefepime, Cefetamet, Cefixime, Cefmenoxime, Cefmetazole, Cefminox, Cefonicid, Cefoperazone, Cefotaxime, Cefotetan, Cefotiam, Ceftiofur, Cefovecin, Cefoxtin, Cefpodoxime, Cefprozil, Cefquinome, Cefradine, Cefminox, Cefsulodin, Ceftaroline, Ceftazidime, Ceftezole, Ceftibuten, Ceftizoxime, Ceftobiprole, Ceftolozane, Ceftriaxone, Cefuroxime, Cefuzoname, Cephalexin, Cephalotin, Flomoxef, Latamoxef, Loracarbef Imipenem, Meropenem, Doripenem, Ertapenem, Biapenem, Panipenem, Faropenem or derivatives thereof.

The antibiotic may be selected from aminoglycosides: Amikacin, Arbekacin, Apramycin, Dibekacin, Gentamicin, Isepamicin, Kanamycin, Neomycin, Netilmicin, Plazomicin, Sisomicin, Spectinomyin, Streptomycin, Tobramycin or derivatives thereof.

The antibiotic may be selected from quinolones: Cinoxacin, Ciprofloxacin, Enofloxacin, Gatifloxacin, Gemifloxacin, Levofloxacin, Moxifloxacin, Nalidixic acid, Norfloxacin, Oxafloxacin, or derivatives thereof.

The antibiotic may be selected from antimicrobial peptides, for example Colistin, Polymyxin B or derivatives thereof.

A pharmaceutical composition as described herein may comprise only one or more than one antibiotic.

A pharmaceutical composition containing a crystalline compound of formula (I) may contain or be co-administered with bactericidal or permeability-increasing-g protein product (BPI) or efflux pump inhibitors to improve activity against gram negative bacteria and bacteria resistant to antimicrobial agents. Antiviral, antiparasitic, antifungal agents may also be administered in combination with the inhibitor compounds.

The pharmaceutical composition may contain complexing agents or anticoagulants, antioxidants, stabilizers, aminoglycosides, pharmaceutically acceptable salts or the like or mixtures thereof.

In particular the pharmaceutical composition may contain β-lactam antibiotics, preferably penicillins, cephalosporins, carbapenem, monobactams, more preferably piperacillin, cefepime; ceftriaxone; meropenem, aztreonam.

The pharmaceutical composition may contain buffers, for example sodium citrate, sodium acetate, sodium tartrate, sodium carbonate, sodium bicarbonate, morpholinopropanesulfonic acid, other phosphate buffers and the like and chelating agents like ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid, hydroxyethylenediaminetriacetic acid, nitrilotriacetic acid, 1,2-diaminocyclohexanetetraacetic acid, bis(2-aminoethyl)ethyleneglycoltetraacetic acid, 1,6-hexamethylenediaminetetraacetic acid and the like or pharmaceutically acceptable salts thereof.

A pharmaceutical composition as described herein may be administered to a human or warm-blooded animal by any suitable method, and preferably by intravenous injection.

EXAMPLES

All XRPD data described herein were acquired in transmission mode on an X'pert Pro instrument with X'celerator detector. The data were evaluated using the Highscore Plus software using copper as radiation source at a wavelength of 1.54 Å.

DSC analyses were run on a TA Q2000 MDSC instrument.

TGA analyses were run on a TA Q5000 instrument. The data were evaluated using Universal Analysis software.

Amorphous (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide, was prepared according to example 1 of WO 2008010048, the contents of which are incorporated herein by reference.

Example 1 Preparation of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide Form A

Amorphous (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide (200 mg) was dissolved in ethanol 96% (0.5 mL). The solution was stirred at 20° C., after 30 minutes a solid was formed. The mixture was stirred for 4 hours at 20° C. and the solid was isolated by filtration and dried overnight at room temperature in a vacuum oven. The obtained product (30 mg) was crystalline Form A which was characterized by an XRPD pattern as shown in FIG. 1 and summarized in Table 1.

d-spacing Angle [°2θ] [Å] 8.8223 10.01516 12.0725 7.32517 14.4346 6.13137 14.9183 5.93364 16.2594 5.44711 18.2478 4.85778 19.0618 4.65213 19.7798 4.48485 20.8191 4.26326 23.5119 3.78074

DSC (FIG. 5) showed the sample to have a melting endotherm with a maximum at 163° C. TGA thermal curve is shown in FIG. 9.

An optical microscope image of Form A is shown in FIG. 13.

Example 2 Preparation of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide Form A

Amorphous (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide (1 g) was suspended in ethanol 96% (3 mL). The resulting mixture was filtered through a syringe filter. The saturated solution was treated with methyl tert-butyl ether (0.5 mL) as antisolvent. The antisolvent addition results in a solid precipitation. The mixture was stirred at room temperature overnight and the solid was isolated by filtration and dried overnight at room temperature in a vacuum oven. The solid recovered was crystalline Form A characterized by XRPD concordant with XRPD pattern given in Example 1.

Example 3 Preparation of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide Form A

Amorphous (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide (1 g) was suspended in ethanol 96% (5 mL). The resulting mixture was filtered through a syringe filter. A pinch of Form A material was added to the solution as seed. The seed was not dissolved and the saturated solution was treated with heptane (0.5 mL) as antisolvent. The antisolvent addition results in a solid precipitation. The mixture was stirred at room temperature overnight and the solid was isolated by filtration and dried overnight at room temperature in a vacuum oven. The solid recovered was crystalline Form A characterized by XRPD concordant with XRPD pattern given in Example 1.

Example 4 Preparation of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide Form A

Amorphous (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide (1 g) was suspended in ethanol 96% (5 mL). The resulting mixture was filtered through a syringe filter. A pinch of Form A material was added to the solution as seed. The seed was not dissolved and the saturated solution was treated with 2-propanol (0.5 mL) as antisolvent. The antisolvent addition results in a solid precipitation. The mixture was stirred at room temperature overnight and the solid was isolated by filtration and dried overnight at room temperature in a vacuum oven. The solid recovered was crystalline Form A characterized by XRPD concordant with XRPD pattern given in Example 1.

Example 5 Preparation of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide Form A

Amorphous (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide (4 g) was weighed in a multimax vessel equipped with an impeller stirrer. The solid was suspended in ethanol 96% (32 mL). The mixture was heated to 35° C. and stirred at 800 RPM. At 35° C. the starting material seemed to be dissolved but the solution appeared slightly opaque. Methyl tert-butyl ether (8 mL) as antisolvent was added to the opaque solution over 1 hour. The addition of the antisolvent resulted in a solid formation. The mixture was cooled down to 10° C. over 1 hour. During the cooling ramp the material became sticky and the majority of the material adhered to the vessel walls. The mixture was stirred overnight and the solid obtained was discharged from the vessel by mechanical removal of the sticky solid from the vessel wall. The obtained mixture was filtered under vacuum; the cake was dried at room temperature in a vacuum oven for 60 hours to afford 2.75 g of a white solid. The solid recovered was crystalline Form A characterized by XRPD concordant with XRPD pattern given in Example 1.

Example 6 Preparation of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide Form A

Amorphous (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide (5 g) was weighed in a multimax vessel equipped with an impeller stirrer. The solid was suspended in ethanol 96% (30 mL). The mixture was heated to 35° C. and stirred at 800 RPM. At 35° C. the starting material seemed to be dissolved but the solution appeared slightly opaque. The opaque solution was filtered through a syringe filter to obtain a clear solution. A pinch of Form A material was added to the solution as seed; the seed was not dissolved and the mixture was cooled to 20° C. over 45 minutes. At this temperature methyl tert-butyl ether (10 mL) was added as antisolvent over 20 minutes. The addition of the antisolvent resulted in a sticky solid formation, the majority of the material adhered to the vessel walls. The mixture was stirred overnight and the solid obtained was discharged from the vessel by mechanical removal of the sticky solid from the vessel wall. The obtained mixture was filtered under vacuum; the cake was dried at room temperature in a vacuum oven for 60 hours to afford 3.61 g of a white solid. The solid recovered was crystalline Form A characterized by XRPD concordant with XRPD pattern given in Example 1.

Example 7 Preparation of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide Form A

Amorphous (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide (7 g) was weighed in a multimax vessel equipped with an impeller stirrer. The solid was suspended in ethanol 96% (21 mL). The mixture was heated to 40° C. and stirred at 400 RPM. At 40° C. the starting material seemed to be dissolved but the solution appeared slightly opaque. The opaque solution was filtered through a syringe filter to obtain a clear solution. A pinch of Form A material was added to the solution as seed; the seed was not dissolved and the mixture was stirred at 40° C. for 1 hour. The mixture is then cooled to 10° C. over 5 hours and stirred for 60 hours. The obtained material adhered to the vessel walls and was discharged by mechanical removal of the sticky solid from the vessel wall. The obtained mixture was filtered under vacuum; the cake was dried at room temperature in a vacuum oven for 18 hours to afford 5.54 g of a white solid. The solid recovered was crystalline Form A characterized by XRPD concordant with XRPD pattern given in Example 1.

Example 8 Preparation of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide Form B

Amorphous (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide (200 mg) was suspended in acetone (0.5 mL) and the slurry was stirred for 4 hours at 40° C. The solid was isolated by filtration and dried overnight at room temperature in a vacuum oven. The obtained product (150 mg) was crystalline Form B which was characterized by an XRPD pattern as shown in FIG. 2 and summarized in Table 2.

Angle d-spacing [°2θ] [Å] 9.3736 9.42739 10.343 8.54587 12.5922 7.024 13.172 6.71609 14.998 5.90227 15.636 5.66284 18.5083 4.79001 19.1049 4.64175 20.7935 4.26845 23.9264 3.71616

DSC (FIG. 6) showed the sample to have a melting endotherm with a maximum at 180° C. TGA thermal curve is shown in FIG. 10.

An optical microscope image of Form B is shown in FIG. 14.

Example 9 Preparation of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide Form C

Amorphous (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide (5 g) was weighed in a multimax vessel equipped with an impeller stirrer. The solid was suspended in ethanol HPLC grade 99.8% (20 mL). The mixture was heated to 40° C. and stirred at 500 RPM. At 40° C. the starting material seemed to be dissolved but the solution appeared slightly opaque. The opaque solution was filtered through a syringe filter to obtain a clear solution. The solution was cooled to 36° C. over 15 minutes and Form B material (30 mg) was added to the solution as seed; the seed was not dissolved and promoted the product crystallization. The mixture was stirred at 36° C. for 30 minutes and is then cooled to 15° C. over 3.5 hours. The slurry was aged overnight and then was filtered under vacuum; the cake was dried at room temperature in a vacuum oven for 18 hours to afford 3.7 g of a white solid. The obtained product was crystalline Form C which was characterized by an XRPD pattern as shown in FIG. 3 and summarized in Table 3.

Angle d-spacing [°2θ] [Å] 9.331 9.47026 10.7259 8.24161 14.8509 5.96039 15.2924 5.7893 15.7717 5.61443 16.1565 5.48158 18.6025 4.76595 20.1156 4.41074 20.9959 4.22776 23.2215 3.82734

DSC (FIG. 7) showed the sample to have a melting endotherm with a maximum at 185° C.

TGA thermal curve is shown in FIG. 11.

An optical microscope image of Form C is shown in FIG. 15.

Comparative Example

The XRPD spectrum of amorphous (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide prepared as described in WO 2008/010048 is shown in FIG. 4. No crystalline character is detectable in this spectrum.

Solubility Evaluation

Solubility values of solvents were calculated with respect to the HPLC response factor, set out in FIG. 12.

HPLC response factor was calculated for the amorphous compound of formula (I) using samples dissolved in acetonitrile/water 9/1 with the following method:

Column: ZORBAX Eclipse XDB-C18 (150×4.6 mm, 5 μm) Temperature: 25° C.

Mobile phase: A: 0.05M Sodium ortophosphate/water, B: Acetonitrile Gradient: from 5% of B to 95% of B in 10 min Detector. UV λ=220 nm

Concentration HPLC Sample (mg/ml) area 1 0.62 333.445 2 1.24 660.935 3 1.68 1219.92 4 2.25 1643.32 5 2.30 1940.44 6 3.10 2830.31

Slurries of the amorphous compound of formula (I) in the selected solvents were prepared and stirred at 20° C. and 40° C. for 4 hours.

Samples of each slurry were filtered and the mother liquors injected in HPLC.

The solid residual were isolated and analyzed by XRPD.

The results are summarized in the following Table 4.

TABLE 4 Solubility of amorphous compound of formula (I) Solubility (mg/ml) Solvent 20° C. 40° C. Acetone 0 0 Ethanol 420 >420 Ethyl acetate 0 0 Methyl tert-butyl ether 0 0 Heptane 0 0 Water >400 >400 2-propanol 23 28 Iso-propyl acetate 0 0 Di-isopropyl ether 0 0 Methanol >400 >400 Methylethyl ketone 0 0 Tetraydrofurane 0 0 Anisolo 0 0 Tert-butyl acetate 0 0 Dimethylsulfoxide >400 >400 1-propanol 295 >400 1-butanol 97 167 Acetonitrile 6 n.a. Chlorobenzene 0 n.a. Dichloromethane 0 n.a. 1,4-dioxane 0 n.a. Ethanol/methyl tert-butyl ether 20% 52 n.a. Ethanol/methyl tert-butyl ether 40% 16 n.a. Ethanol/acetone 20% >300 n.a. Ethanol/acetone 40% >300 n.a.

Form a Characterization by Raman Spectrum and Fourier Transform Infrared Spectroscopy (FT-IR)

The Raman spectrum of Form A is shown in FIG. 16 with the related peak bands list in Table 5.

Peak List:

Position Intensity 247.89 4066.127 268.70 4076.600 285.77 5666.532 297.80 7186.507 322.04 4385.802 411.78 3861.458 436.26 2433.529 499.66 2023.949 521.68 4054.372 560.04 2419.952 588.92 1163.452 629.52 6647.466 640.58 4792.760 687.14 1836.374 718.78 1714.527 758.37 1345.186 794.58 2302.231 836.54 1806.043 872.19 5315.287 932.18 1889.917 949.44 2637.407 962.31 2419.830 985.74 2736.112 1049.63 5534.104 1074.79 2056.236 1097.28 4171.412 1135.89 5311.271 1148.59 3581.329 1178.28 2121.957 1215.25 2643.923 1239.16 3338.948 1266.18 3677.753 1325.12 8522.793 1368.61 5404.136 1394.52 6973.028 1425.05 4802.836 1457.84 5583.813 1534.20 4855.332 1648.81 3369.165 1773.12 4261.622 2890.60 6428.710 2962.11 19794.615 2986.55 7243.053 3015.84 7382.472 3049.43 4000.206

FIG. 17 shows the FT-IR spectrum of Form A with the related peak bands list in Table 6.

Peak List

Position Intensity 673.84 0.0846 686.51 0.118 718.98 0.111 756.67 0.0942 781.58 0.0916 797.38 0.100 834.89 0.0756 871.89 0.0672 932.05 0.0646 948.44 0.0932 1025.16 0.0712 1050.31 0.0580 1075.14 0.0752 1094.42 0.113 1134.65 0.124 1148.93 0.106 1204.60 0.0957 1240.06 0.0661 1235.85 0.0661 1309.76 0.147 1363.83 0.0819 1392.60 0.0512 1425.57 0.0468 1452.48 0.0538 1533.83 0.0601 1622.97 0.119 1766.49 0.109 2890.12 0.0390 2964.73 0.0446 3013.48 0.0440 3049.64 0.0414 3089.32 0.0425 3343.53 0.0427 3530.97 0.0395

Form C Characterization by Raman Spectrum and FT-IR

The Raman spectrum of Form C is shown in FIG. 18 with the related peak bands list in Table 7.

Peak List:

Position Intensity 240.20 4128.340 278.20 10739.558 299.77 10722.921 316.97 8908.874 389.49 3492.405 403.91 5676.352 419.31 6378.482 438.01 3159.695 514.23 9161.536 540.24 2881.736 560.59 5050.867 624.85 13700.852 640.80 5770.215 692.53 7222.112 715.48 2197.299 753.71 2920.133 800.11 2731.873 839.41 3232.516 868.99 6613.900 938.91 4443.281 967.79 3605.101 985.96 4480.407 1033.35 5823.568 1049.82 6638.105 1096.10 10022.146 1141.01 9717.918 1180.11 4361.805 1197.40 3267.057 1235.20 3502.896 1317.60 10464.665 1362.32 6745.435 1395.94 9937.875 1457.27 6235.580 1535.79 4771.901 1640.00 4841.217 1775.78 7336.955 2879.07 5109.468 2909.71 11865.885 2947.89 19208.596 2958.72 17883.816 2983.99 21848.400 2999.93 12395.464 3014.33 15550.745 3084.97 4124.013 3169.92 8548.841

The FT-IR spectrum of Form C is shown in FIG. 19 with the related peak bands list in Table 8.

Peak List:

Position Intensity 671.04 0.103 691.08 0.151 715.10 0.126 752.68 0.145 780.33 0.117 790.47 0.149 799.40 0.136 838.87 0.0751 868.41 0.0772 939.45 0.111 956.58 0.106 985.83 0.0629 1023.40 0.101 1089.49 0.135 1098.28 0.145 1138.00 0.213 1195.45 0.166 1233.08 0.0960 1269.19 0.142 1309.02 0.208 1361.03 0.114 1387.96 0.0675 1456.72 0.0694 1536.21 0.0645 1637.71 0.174 1770.33 0.174 2972.20 0.0498 3015.04 0.0553 3083.68 0.0481 3168.20 0.0456 3375.47 0.0422

The analyses performed on Form A and Form C, including the information collected on the influence of the water content during the crystallization, has supported the hypothesis that Form A is a hydrate form with a rapid water exchange with the ambient and Form C is a more stable anhydrous form. Therefore, Form C was selected for further optimisation and scale-up of the crystallization process, and assessments as described below.

Optimization of Form C Crystallization Example 10 Crystallization Procedure Using a Form C Seed Preparation of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide Form C

Amorphous (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide (5 g) was weighed in a 50 ml multimax vessel equipped with an impeller stirrer. The solid was suspended in 20 ml of ethanol HPLC grade 99.8%. The mixture was heated to 40° C. and stirred at 700 RPM. At 40° C. the starting material was dissolved. The solution was cooled to 36° C. over 15 minutes and Form C material (27 mg) was added to the solution as seed; the seed was not dissolved and promoted the product crystallization. The mixture was cooled to 15° C. over 3.5 hours. The slurry was aged overnight and then was filtered under vacuum; the cake was dried at 30° C. in a vacuum oven for 40 hours to afford 3.7 g of a white solid. The solid showed an XRPD pattern for Form C.

The quality of the ethanol system was also investigated in the production of Form C material using 96% ethanol instead of ethanol HPLC grade 99.8% as described in Example 11.

Example 11 Preparation of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide Form A

Amorphous (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide (5 g) was weighed in a 50 ml multimax vessel equipped with an impeller stirrer. The solid was suspended in 20 ml of ethanol 96%. The mixture was heated to 40° C. and stirred at 700 RPM. At 40° C. the starting material seemed to be dissolved but the solution appeared slightly opaque. The opaque solution was filtered through a syringe filter to obtain a clear solution. The solution was cooled to 35° C. over 15 minutes and Form C material (28 mg) was added to the solution as seed. After 10 minutes at 35° C. was dissolved. The temperature was lowered to 30° C. over 15 minutes and more Form C material (27 mg) was added as seed. The seed was dissolved after 15 minutes. The solution was heated up to 35° C. and a pinch of Form B material was added to the solution but was dissolved after few minutes. A pinch of Form A material was added as seed; this time the seed did not dissolve and promoted the product crystallization. The mixture was cooled to 15° C. over 3.5 hours. The slurry was aged overnight and then was filtered under vacuum; the cake was dried at 30° C. in a vacuum oven for 18 hours to afford 3.1 g of a white solid. The solid showed an XRPD pattern concordant to Form A.

Examples 10 and 11 procedures demonstrate that the water content in the ethanol system can affect production of Forms A and C by a seeded approach. The formation of Form A material is possible in ethanol 96%, whereas the formation of Form C from a Form C crystal required use of ethanol HPLC grade 99.8%.

Example 12 Preparation of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide Form C

Amorphous (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide (8 g) was weighed in a 50 ml Multimax vessel equipped with an impeller stirrer. The solid was suspended in 20 ml of ethanol HPLC grade 99.8%. The mixture was heated to 40° C. and stirred at 800 RPM. At 40° C. the starting material was dissolved. The solution was cooled to 36° C. over 10 minutes and Form C material (24 mg) was added to the solution as seed; the seed was not dissolved and promoted the product crystallization. After 15 minutes stirring at 36° C. the mixture was cooled to 15° C. over 3.5 hours. The slurry was aged overnight and then was filtered under vacuum in nitrogen atmosphere (a funnel connected to a nitrogen flux was put over the filter). The cake was washed with 8 ml of ethanol HPLC grade 99.8%. The cake was dried inside the filter at 30° C. in a vacuum oven for 2 hours, after this time the product was transferred to a crystallizer and dried for further 16 hours. The product was analyzed by ¹H-NMR to check the solvent content and showed the presence of ˜1.3% w/w of ethanol. The cake was further dried at 35° C. in the vacuum oven for 6 hours. A new sample was taken and analyzed by ¹H-NMR for solvent content. The ethanol residual was comparable to the first sample. The product was stored at −20° C. for the week-end and then put in the vacuum oven at 40° C. for 24 hours to yield 6 g of the product. The solid showed an XRPD pattern concordant with Form C. ¹H-NMR confirmed the presence of ˜1.3% w/w of ethanol residual in the cake.

The decrease of the seed loading did not have any negative impact on the product crystallization and was implemented in the scaled-up procedure as described in Example 13.

Example 13 Preparation scale up of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide Form C at 36 g scale

Amorphous (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide (36.45 g) was weighed in a 250 ml multimax vessel equipped with an impeller stirrer. The solid was suspended in 146 ml of ethanol HPLC grade 99.8%. The mixture was heated to 40° C. over 20 minutes. After 15 minutes at 40° C. the starting material was completely dissolved and the solution was cooled to 36° C. over 10 minutes and Form C material (110 mg) was added to the solution as seed; the seed was not dissolved and promoted the product crystallization. After 10 minutes stirring at 36° C. the mixture was cooled to 15° C. over 3.5 hours. The obtained mixture was aged overnight and then was filtered under vacuum. The cake was washed with 40 ml of ethanol HPLC grade 99.8% and three times with 40 ml of methyl tert-butyl ether to remove residual ethanol from the cake. The cake was deliquored in nitrogen atmosphere (a funnel connected to a nitrogen flux was put over the filter) under vacuum. The cake was dried in a vacuum oven for 24 hours to yield 26.8 g of the final product as a white solid.

The solid was analyzed by XRPD, TGA, optical microscopy (OM) and ¹H-NMR.

The XRPD analysis of the product showed crystalline material with a pattern consistent with Form C (FIG. 20).

The TGA analysis for the product (FIG. 21) shows a weight loss of circa 2% up to 120° C. probably due to adsorbed water and solvent residual.

The OM analysis in FIG. 22 shows Form C crystals. Birefringent particles using polarized light could be seen.

The ¹H-NMR spectrum (FIG. 23) is consistent with the structure of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide. The ethanol residue was calculated comparing the ethanol signal at 1.06 ppm and the API signal at 1.40 ppm. Considering integrals values, number of protons and the molecular weight of the reference signals the estimated ethanol residue is equal to 0.4% w/w respect to the API.

Solubility Assessment in Saline Physiological Solution

The Form C solubility was calculated by HPLC employing a dedicated walk-up method. The product obtained by the scaled up procedure described in Example 13 was used to perform the experiments.

1.9 g of the product was suspended in 1 ml of commercial physiologic solution (0.9% of NaCl) at ambient temperature (˜20° C.). The suspension resulted slightly opaque and quite viscous after 30 min. After this time the suspension was sampled and the sample injected in HPLC to determine its concentration. After 2 hrs stirring the solid residue was completely dissolved. The addition of more solid was not performed to avoid the gelatinisation of the viscous solution. A sample was taken and injected in HPLC to determine its concentration. The solution was stirred other 3 hrs and sampled again. The 5 hrs sample was also injected in HPLC to determine its concentration. The HPLC traces did not show the formation of significant impurities. Table 9 shows the solubility results for the time-points selected.

Physiological Solubility (mg/ml) at solution Timepoint ambient temperature 1 30 mins 772 2 12 hours >883 3  5 hours >812

Particle Size Distribution

The particle size analysis was performed on the product obtained by the scaled up procedure described in Example 13 using the procedure described below. Three measurements for each suspension were recorded and the results are shown in FIG. 24 and in Table 10.

Sample Name d (0.1) d (0.5) d (0.9) Suspension 1, Measurement 1 29.08 129.34 249.92 Suspension 1, Measurement 2 28.94 128.69 246.31 Suspension 1, Measurement 3 28.90 128.42 247.37 Suspension 2, Measurement 1 28.26 130.37 251.74 Suspension 2, Measurement 2 26.80 125.95 248.77 Suspension 2, Measurement 3 25.40 119.25 239.11 Suspension 3, Measurement 1 28.54 133.06 256.35 Suspension 3, Measurement 2 26.85 128.64 249.66 Suspension 3, Measurement 3 26.09 126.42 244.15 Average 27.65 127.79 248.15

Example 14 Preparation of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide Form D

Amorphous (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide (30 g) was suspended in 200 mL of N,N-dimethylformamide, pre-heated to +20/25° C. After 5 minutes stirring a solution is obtained and after few minutes of stirring crystallization takes place. The suspension is stirred for about 2 hours. Then the suspension is cooled down to 0/+5° C. and stirred for about 2 hours.

The obtained solid is filtered and washed with 50 mL of N,N-dimethylformamide pre-cooled to 0/+5° C. The wet product is then suspended in 300 mL of dichloromethane and the temperature is adjusted to +30/32° C. The suspension is stirred for 45 minutes then the solid is filtered and washed with 100 mL of dichloromethane pre-heated to +30/32° C. The product is dried under vacuum at +40° C. until constant weight is achieved. The obtained product (19.3 g) was crystalline form D which was characterized by an XRPD pattern as shown in FIG. 25 and summarized in the following Table 11.

d-spacing No. Angle [°2θ] [Å] Height (cps) FWHM (deg) Int. deg Int. 1 6.7824 13.02204 369.45 0.2491 119.22 0.3227 333.64 2 9.5032 9.29904 105.18 0.2064 26.05 0.2477 403.40 3 10.4510 8.45774 31.17 0.2565 10.15 0.3256 324.89 4 11.6074 7.61762 109.02 0.2733 31.72 0.2910 305.11 5 12.7850 6.91847 41.58 0.2692 11.91 0.2865 310.18 6 13.4325 6.58642 64.83 0.2025 13.98 0.2156 412.47 7 14.2560 6.20776 275.43 0.2923 86.51 0.3141 286.05 8 15.4567 5.72810 77.92 1.8085 152.28 1.9543 46.30 9 16.3961 5.40199 835.69 0.4340 388.58 0.4650 193.15 10 17.1082 5.17871 522.62 0.3370 188.77 0.3612 249.00 11 18.2742 4.85081 148.14 0.3388 53.91 0.3639 248.02 12 20.0651 4.42173 194.88 0.5228 109.82 0.5635 161.19 13 20.6373 4.30040 624.11 0.3160 211.90 0.3395 266.91 14 22.7520 3.90524 167.10 0.2473 44.02 0.2635 342.21 15 23.2376 3.82472 236.56 0.6238 157.13 0.6642 135.79 16 23.6811 3.75409 198.42 0.5077 107.27 0.5406 167.00 17 25.6817 3.46600 163.48 0.4133 71.93 0.4400 205.89 18 26.1802 3.40112 205.89 0.5004 109.66 0.5326 170.25 19 26.9957 3.30020 138.32 0.4481 65.98 0.4770 190.41 20 27.7606 3.21098 221.24 0.3671 86.44 0.3907 232.85 21 28.7686 3.10073 75.61 0.2697 21.70 0.2870 317.65 22 30.4020 2.93775 125.52 0.3451 46.72 0.3722 249.17 23 31.4633 2.84104 102.42 0.6496 72.49 0.7078 132.70 24 32.4753 2.75478 268.97 0.4635 134.78 0.5011 186.43 25 34.4252 2.60307 21.60 0.6492 14.92 0.6911 133.80 26 34.9492 2.56524 12.83 0.4399 6.01 0.4682 197.76 27 36.0489 2.48946 80.97 0.3230 27.84 0.3438 270.15 28 38.4794 2.33762 119.18 0.6568 83.33 0.6992 133.80 29 40.2292 2.23989 27.09 0.9554 27.55 1.0170 92.49 30 42.6703 2.11723 63.61 0.5331 36.10 0.5675 167.09 31 43.9731 2.05748 22.45 0.4622 11.29 0.5030 193.59 32 53.8897 1.69994 16.28 0.5850 11.95 0.7339 159.10

The Raman spectrum of Form D is shown in FIG. 26 with the related peak band list in the following Table 12 (using Raman Jasco RFT-600 instrument, light source Nd-YAG, 1064 nm: exciting wavelength).

Peak Wave number Y value 1 3157.83 0.0281958 2 3009.34 0.072899 3 2974.63 0.100304 4 2904.24 0.0444922 5 1772.23 0.0339617 6 1663.27 0.0258104 7 1474.28 0.0302334 8 1458.85 0.0264177 9 1437.64 0.0373852 10 1400.04 0.0571817 11 1352.79 0.0302512 12 1302.65 0.0862235 13 1195.62 0.0247634 14 1175.37 0.0330307 15 1138.73 0.0701386 16 1092.45 0.11397 17 1031.7 0.0433419 18 993.13 0.0292598 19 947.811 0.0372661 20 874.529 0.0711543 21 838.853 0.028534 22 783.892 0.0241906 23 688.432 0.0231856 24 661.434 0.0387182 25 624.793 0.134281 26 556.332 0.0499649 27 514.87 0.0831978 28 433.875 0.0597285 29 414.59 0.0366139 30 340.344 0.0295258 31 324.916 0.058052 32 287.311 0.0680197 33 249.706 0.0476452

Example 15 Preparation of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide Form E

Amorphous (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide (5 g) was suspended in 30 mL of N,N-dimethylformamide, pre-heated to +20/25° C. After 5 minutes of stirring, a solution is obtained and after few minutes a crystallization takes place. The suspension is stirred for about 2 hours.

The obtained solid is filtered and washed with 12.5 mL of N,N-dimethylformamide. The wet product is then suspended in 100 mL of ethyl acetate and the temperature is adjusted to +40/45° C. The suspension is stirred for 60 minutes then the solid is filtered and washed with 50 mL of ethyl acetate pre-heated to +40/45° C.

Finally the product is dried under vacuum at +40° C. till constant weight is achieved.

The obtained product (2.4 g) was crystalline form E which was characterized by an XRPD pattern as shown in FIG. 27 and summarized in the following Table 13.

d-spacing No. Angle [°2θ] [Å] Height (cps) FWHM (deg) Int. deg) Int. 1 6.8269 12.93732 260.98 0.2205 68.42 0.2622 376.99 2 9.5377 9.26545 102.12 0.2256 29.95 0.2933 369.14 3 10.4196 8.48314 117.20 0.2867 38.29 0.3267 290.56 4 11.6525 7.58825 82.26 0.2299 20.13 0.2447 362.76 5 12.6274 7.00451 83.34 0.3681 32.66 0.3919 226.76 6 13.3413 6.63125 95.57 0.3884 39.52 0.4135 215.07 7 14.2802 6.19726 104.47 0.2212 26.92 0.2577 378.06 8 15.0475 5.88296 494.41 0.3508 199.68 0.4039 238.55 9 15.6848 5.64531 378.40 0.3968 173.35 0.4581 211.11 10 16.4735 5.37678 557.04 0.3770 234.97 0.4218 222.38 11 17.1773 5.15801 229.03 0.3175 81.31 0.3550 264.28 12 18.4488 4.80530 297.04 0.3867 122.28 0.4117 217.36 13 19.0164 4.66312 93.86 0.2902 28.99 0.3089 289.90 14 20.0808 4.41830 143.91 0.4955 75.93 0.5276 170.05 15 20.6999 4.28752 421.62 0.3301 148.17 0.3514 255.52 16 22.2167 3.99811 90.66 0.6225 62.16 0.6857 135.85 17 22.7863 3.89944 130.42 0.4242 61.57 0.4721 199.52 18 23.3436 3.80760 273.25 0.4007 120.48 0.4409 211.43 19 23.8843 3.72261 447.75 0.4942 242.53 0.5417 171.61 20 25.3818 3.50627 95.40 1.0693 109.22 1.1449 79.54 21 26.2231 3.39566 113.17 0.5204 63.45 0.5606 163.70 22 27.8574 3.20005 112.17 0.2916 35.41 0.3157 293.14 23 29.9383 2.98219 52.64 0.4091 38.32 0.7279 209.96 24 31.3100 2.85459 70.72 0.3247 40.45 0.5720 265.41 25 33.3041 2.68809 41.89 0.3114 17.99 0.4295 278.15 26 38.5117 2.33574 15.66 1.2693 21.16 1.3512 69.24 27 41.1953 2.18957 21.01 1.1036 24.69 1.1748 80.32 28 49.2559 1.84846 16.52 0.9722 17.90 1.0835 93.88

The Raman spectrum of Form E is shown in FIG. 28 with the related peak band list in the following Table 14 (using Raman Jasco RFT-600 instrument, light source Nd-YAG, 1064 nm: exciting wavelength).

Peak Wave number Y value 1 3158.8 0.0221892 2 3051.77 0.0289691 3 3011.27 0.0722239 4 2973.67 0.168653 5 2900.38 0.0707581 6 1772.23 0.0829712 7 1482 0.036189 8 1438.61 0.0318463 9 1397.14 0.0563706 10 1352.79 0.0498639 11 1302.65 0.120509 12 1266.01 0.0335002 13 1202.37 0.0466914 14 1185.01 0.0332323 15 1139.69 0.0742465 16 1092.45 0.128341 17 1031.7 0.0532132 18 989.273 0.0474664 19 949.74 0.0622083 20 873.565 0.0993489 21 836.924 0.0338838 22 782.927 0.0376849 23 715.431 0.0287148 24 589.397 0.028656 25 646.006 0.0458421 26 624.793 0.177092 27 556.332 0.0561384 28 613.906 0.109643 29 433.875 0.0568177 30 407.84 0.0759362 31 325.881 0.68886 32 288.276 0.0859623 33 254.527 0.050626 34 216.922 0.0240766

Example 16 Preparation of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide Form F

Amorphous (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide (130 g) was suspended in 800 mL of N,N-dimethylformamide, pre-heated to +20/25° C. 100 mL of N,N-dimethylformamide was added to wash the walls of the flask. After 5 minutes stirring a solution is obtained and after few minutes of stirring crystallization takes place. The suspension is stirred for about 3 hours. Then the suspension is cooled down to 0/+5° C. and stirred for about 3 hours.

The obtained solid is filtered and washed with 300 mL of N,N-dimethylformamide pre-cooled to 0/+5° C. The wet product is then suspended in 700 mL of ethyl acetate and the temperature is adjusted to +40/45° C. The suspension is stirred for 30 minutes then the solid is filtered and washed with 150 mL of ethyl acetate pre-heated to +40/45° C. The procedure with the suspension in Ethyl acetate is repeated twice. Finally the product is dried under vacuum at +40° C. till constant weight is achieved.

The obtained product (65-66 g, molar yield about 76%, with an assay of 98-99% was crystalline form F, which was characterized by an XRPD pattern as shown in FIG. 29 and summarized in the following Table 15.

Angle d-spacing No. [°2θ] [Å] Height (cps) FWHM (deg) Int. deg) Int. 1 8.5718 10.30725 116.72 0.1981 26.19 0.2244 419.96 2 10.3165 8.56773 182.16 0.2142 42.67 0.2343 388.97 3 12.7398 6.94292 420.49 0.2216 103.83 0.2469 376.75 4 15.3615 5.76339 870.60 0.2471 241.26 0.2771 338.84 5 15.9547 5.55042 1374.98 0.2605 400.47 0.2913 321.60 6 16.4290 5.39123 1343.96 0.2344 352.88 0.2626 357.69 7 17.1990 5.15158 477.25 0.2281 118.86 0.2490 367.89 8 18.1207 4.89155 531.20 0.2398 146.12 0.2751 350.36 9 20.4870 4.33160 915.19 0.2443 275.10 0.3006 345.16 10 21.4040 4.14805 37.20 0.1769 7.01 0.1884 477.23 11 22.8548 3.88791 528.69 0.2904 164.14 0.3105 291.53 12 23.2204 3.82751 502.41 0.3500 188.64 0.3755 242.00 13 23.4688 3.78756 292.42 0.1501 47.04 0.1609 564.73 14 24.4199 3.64215 132.35 0.2404 34.95 0.2641 353.09 15 25.6394 3.47163 359.02 0.2563 104.03 0.2897 331.96 16 25.9983 3.42450 94.56 0.2531 27.13 0.2869 336.47 17 26.2914 3.38699 134.69 0.2951 45.04 0.3344 288.79 18 27.0457 3.29421 387.38 0.3463 151.47 0.3910 246.47 19 27.6934 3.21862 412.53 0.2941 136.95 0.3320 290.62 20 28.7394 3.10381 190.86 0.2739 56.91 0.2982 312.74 21 29.7603 2.99962 32.77 0.2736 9.54 0.2913 313.76 22 30.3078 2.94667 222.03 0.2854 67.46 0.3038 301.19 23 31.4660 2.84080 125.87 0.5371 71.97 0.5717 160.49 24 32.3054 2.76888 98.55 0.2002 21.00 0.2131 431.51 25 32.4785 2.75451 363.46 0.4069 157.43 0.4331 212.38 26 33.1981 2.69643 37.54 0.2403 9.60 0.2558 360.31 27 33.7446 2.65401 15.05 0.5057 8.10 0.5383 171.46 28 34.3283 2.61020 55.64 0.1955 11.58 0.2081 444.20 29 35.0200 2.56021 21.77 0.6046 14.01 0.6435 143.92 30 35.9880 2.49354 133.13 0.2751 38.98 0.2928 317.16 31 38.4256 2.34077 142.45 0.6826 103.50 0.7266 128.73 32 40.2911 2.23659 56.34 0.4183 25.09 0.4453 211.28 33 40.8969 2.20485 33.86 0.3473 12.52 0.3697 254.95 34 42.6047 2.12034 130.78 0.2718 59.44 0.4545 327.66 35 43.7327 2.06823 39.36 0.5339 22.37 0.5684 167.46 36 44.8088 2.02103 29.53 0.2009 6.31 0.2138 446.84 37 53.9562 1.69800 23.47 0.6255 15.68 0.6680 148.86

Raman spectra for three bathes of Form F are shown in FIGS. 30 and 31.

Both XRPD and Raman spectra acquired for different batches of Form F product are overlapping.

Scanning electron microscopy images of samples of the three batches of Form F are shown in FIGS. 32-50. The SEM images of the samples were obtained using a JEOL JSM 5500 LV scanning electron microscope, operating at 30 kV in low vacuum (30 Pa) with the backscattered electron technique.

Form F Characterization by FT-IR, DSC, TGA, EGA

FIG. 51 shows the FT-IR spectrum of Form F with the related peak bands list in Table 16.

Peak List:

Position Intensity 502 50.668 514 59.193 538 66.311 554 48.279 586 76.021 623 60.523 635 58.506 675 73.819 688 65.213 711 63.330 752 53.517 783 68.207 808 55.605 826 52.413 872 72.360 908 81.158 928 78.947 948 62.908 953 63.041 989 78.973 1020 62.785 1067 55.907 1088 52.453 1102 46.426 1136 35.517 1186 50.232 1199 50.943 1228 75.847 1266 64.974 1300 44.572 1307 44.644 1351 62.003 1396 78.685 1472 75.504 1525 78.318 1637 36.877 1735 80.927 1771 48.478 1783 51.962 2898 88.274 2972 84.793 3017 86.781 3051 88.751 3156 84.061

The DSC profile of form F is presented in FIG. 52. The DSC profile shows an exothermic peak at approximately 184° C. (Onset 175° C.) associated with the degradation of the sample.

The Thermo Gravimetric Analysis (TGA) profile of Form F presented on FIG. 53 shows a significant weight loss after approximately 160° C. associated with the degradation of the sample. That is further confirmed by an Evolved Gas Analysis (EGA) shown in FIG. 54. The EGA evidences that the event observed in TGA analysis is caused by the loss of degradation products (e.g. carbon dioxide, sulphur dioxide, etc).

Form F Characterization by Dynamic Vapor Sorption (DVS)

Kinetic moisture sorption measurements were performed at 25° C. and at relative humidity (RH % target as follows:

-   -   From 40% RH to 90% RH     -   Form 90% RH to 0% RH     -   From 0% RH to 90% RH     -   From 90% RH to 0% RH

The obtained results are presented in FIG. 55, wherein the red line traces the percentage changes in mass as function of the time, while the blue line traces the relative humidity changes as function of the time.

DVS isotherms plots are reported in FIG. 56, wherein the red line depicts the first sorption phase, the blue line depicts the first desorption phase, the green line depicts the second sorption phase and the pink line depicts the second desorption phase.

The DVS analyses show that Form F is stable at up to approximately 50% RH and that at 90% RH, the sample showed a weight increase that is greater than 50% w/w. After this event the sample releases and takes water reversibly.

Stability of Form F

The sample becomes a viscous liquid after a day at 25° C. and 60% RH and after a day at 60° C. and 75% RH.

Hygroscopicity of Form F

The hygroscopicity was calculated using the following equation:

% Weight Change=[(W2−W1)/W1]*100

wherein, W1 is weight of sample at the start of the experiment; and W2 is weight of sample at 25° C. and 80% RH in the first absorption cycle.

Obtained results show that the sample is very hygroscopic, with a mass increase that is greater than 15%, and becomes a viscous liquid at high humidity.

The analytical methods used for the product assessment are performed as described below.

Analytical Methods HPLC Method

Column: ZORBAX Eclipse XDB-C18 (150×4.6 mm, 5 μm); column temperature 25° C. Mobile phase: A: Sodium dihydrogen orthophosphate dihydrate 0.05 M; B: Acetonitrile

Gradient:

Time (min) % A % B 0 95 5 10 5 95 10.2 95 5 12 95 5 Flow: 1.0 mL/min Detector. UV DAD@220 nm

The obtained crystalline products of (2S,3S,5R)-3-methyl-3-((3-methyl-1H-1,2,3-triazol-3-ium-1-yl)methyl)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide Form A, B, C, D, E and F have an HPLC purity of at least 98%, preferably at least 99%, preferably at least 99.5%, preferably at least 99.6%, preferably at least 99.7%, preferably at least 99.8%, preferably at least 99.9%.

NMR

The samples for NMR analysis were prepared by complete dissolution of an appropriate amount of material in approximately 0.75 ml of NMR solvent (DMSO-d6)

¹H NMR spectra were recorded at 25° C. using an either a Varian INOVA 400 MHz NMR Spectrometer equipped with a Varian ATB probe.

Variable number of scans (16-256) was applied, using standard acquisition parameters. The pre-acquisition delay was set to 10 sec whenever NMR quantification was carried out. Appropriate phasing and baseline corrections were applied in processing the spectra.

XRPD

The XRPD spectra were collected in transmission mode on an analytical X'pert Pro instrument with X'celerator detector using a standard Aptuit method. The data were evaluated using the HighScore Plus software. The instrumental parameters used are listed below.

Instrumental parameter Value 2-theta range 2-45 Step size [°2-theta] 0.0170 Time per step [sec] 60.7285 sec Wavelength [nm] 0.154060 (Cu K-Alpha1) Rotation [Yes/No] Yes Slits divergence/ Incident Mask fixed 10 mm; Divergence slits antiscatter. ½, Antiscat.slits ½ on incident beam; 1/32 on diffracted X-ray Mirror Inc. Beam Cu W/Si focusing MPD, Acceptance Angle 0.8°, Length 55.3 mm Temperature Room temperature Humidity values [% RH] Ambient Fixed Slits 0.02 rad fixed Soller slits on incident and diffracted beam Monochromator None Detector type X′celerator (active length 2.122 2 theta degree), scanning mode Sample holder Transmission sample holder. Use Insert to keep thickness at 1 mm, 5 mm diameter Configuration Transmission Generator voltage/current 40 KV/40 mA

Optical Microscopy

Optical microscopy analyses were run on the Leica DM microscope equipped with a double polarizer and digital camera. The method parameters are listed below.

Value Polarized light [Y/N] Yes Magnification [eyepiece] 10x Objective Typically 5x, 10x, 20x, 40x Filter slider Use the best filter to optimize the image

TGA and DSC

The TGA analyses were run on a TA Q5000 instrument or on Mettler Toledo Star System (Form F analysis). The DSC analyses were run on the TA Q2000 MDSC or on the DSC 200 F3 Maia (Form F analysis) instruments. DSC and TGA method details are listed below:

Instrumental parameter Value TGA Balance purge gas [mL/min] 10 Sample purge gas [mL/min] 25 Gas Nitrogen Temperature-Time-Rate Typically from room temperature to 250/350° C. at 10° C./min (TA Q5000 instrument); or to 450° C. at 10°K/min (Mettler Toledo Star System) Typical sample amount [mg] Usually from 2 mg to 20 mg Pan [Pt/Al] Hermetically sealed Al (punched) DSC Cooling [ON/OFF] ON Gas Nitrogen Temperature-Time-Rate From 0° C. to ~160° C. Ramp at 10° C./min (TA Q2000 MDSC); or from 25° C. to ~350° C. Ramp at 10°K/min (DSC 200 F3 Maia). Typical sample amount [mg] Usually from 0.5 mg to 2.5 mg Pan Not hermetic Al (TA Q2000 MDSC); or hermetically sealed Al ((DSC 200 F3 Maia)

Raman

Raman analyses were performed with a Keiser Optical Systems RXN1 MicroRaman with Leica Microscope and digital camera

Instrumental Parameter Value Probe N Objective 50x, 50x LWD, 10x Exposure [sec] Typically 0.5-1 Laser Power [mW] 50-400 Autofocus [Y/N] Typically N Accumulation Typically 10 Cosmic ray filter [Y/N] Y Intensity calibration [Y/N] Y Dark subtract [Y/N] Y

FT-IR

FT-IR analyses were performed with a Thermo Nicolet Nexus 470 FT-IR or with a Thermo Nicolet 6700 FT-IR (Form F analyses).

Instrumental Parameter Value Accessory Attenuated Total Reflectance (ATR) - ZnSe Crystal # of scans 64 Resolution [cm⁻¹]  4 Gain Autogain Detector DTGS KBr Spectral Range [cm⁻¹] 4000-650

Particle Size Distribution

Particle Size Distribution by laser light scattering was performed after developing a wet dispersion method using Malvern Mastersizer 2000 instrument. The method parameters are listed below.

Instrument Malvern Mastersizer 2000 Accessory Hydro2000S+ Parameter Value Stirring speed 1750 rpm Dispersant 0.1% w/v Span85/Cyclohexane Sample Quantity Around 100 mg suspended in 5 mL of dispersant Calculation Model General Purpose - Irregular Optical Model Fraunhofer with 1.426 refractive index for the dispersant Sweeps number 15000 background/15000 sample Laser Obscuration [%] between 5 and 20% (typically 8-12%)

The experiments were conducted using the following sample preparation:

-   -   (i) 100 mg of material were weighted in a 10 ml vial and they         were suspended in 5 mL of dispersant;     -   (ii) once the material was all wetted the suspension was added         into the cell and the vial was washed using additional 5 mL of         the dispersant;     -   (iii) the suspension was measured immediately.

EGA

The EGA analysis was carried out on the gas produced during the TGA analysis.

DVS Analyses Instrument Details

Temperature range: 20-40° C. (standard) Maximum sample mass: (low/high mass instrument) 1 g/4 g Mass change: +/−150 mg Stability (24 hours @25° C. and 0% RH)<5 μg Mass resolution: +/−0.1 μg

Humidity Range: 0-98% RH RH Accuracy: +/−1% RH

Temperature stability: +/−0.1° C. Typical gas flow rate: 100/200 sccm Sample chamber: 40 mm wide×50 mm deep×50 mm high Reservoir volume: 100 ml reservoir capacity Heating system: Peltier+Cartridges

The kinetic moisture sorption measurement was performed at 25° C. and in a RH % range described in the following:

From 40% RH to 90% RH Form 90% RH to 0% RH From 0% RH to 90% RH From 90% RH to 0% RH

The experiment is performed on 10-15 mg of sample and the equilibrium criterion is set as dm/dt<0.002% w/w in 10 min with a maximum step time of 240 min.

Stability Tests

The sample was positioned on the sample holder and stored in the following conditions:

25° C. and 60% RH for 7 days 60° C. and 75% RH for 3 days

The samples were analyzed after the test by XRPD.

Hygroscopicity

The hygroscopicity of the sample was determined using the method reported in the academic article “Efficient throughput method for hygroscopicity classification of an active and inactive pharmaceutical ingredients by water vapor sorption analysis” V. Murikipudi et al., Pharmaceutical Development and Technology, 2013, 18(2): 348-358.

The hygroscopicity was calculated using the following equation:

% Weight Change=[(W2−W1)/W1]*100; wherein

W1 is a weight of sample at the start of the experiment; and W2 is a weight of sample at 25° C. and 80% RH in the first absorption cycle.

Classification Criteria

Non hygroscopic: increase in mass is less than 0.2%; Slightly hygroscopic: increase in mass is less than 2% and equal to or greater than 0.2%; Hygroscopic: increase in mass is less than 15% and equal to or greater than 2%; Very Hygroscopic: increase in mass is equal to or greater than 15%; and Deliquescent: sufficient water is absorbed to form a liquid.

Although the present invention has been described in terms of specific exemplary embodiments, it will be appreciated that various modifications, alterations and/or combinations of features disclosed herein will be apparent to those skilled in the art without departing from the scope of the invention as set forth in the following claims. 

1. A crystalline compound of formula (I):


2. A crystalline compound according to claim 1 characterized by an XRPD spectrum comprising four or more peaks selected from peaks with 2θ angles of: 8.82±0.1 degrees 2θ, 12.07±0.1 degrees 2θ, 14.43±0.1 degrees 2θ, 14.92±0.1 degrees 2θ, 16.26±0.1 degrees 2θ, 18.25±0.1 degrees 2θ, 19.06±0.1 degrees 2θ, 19.78±0.1 degrees 2θ, 20.82±0.1 degrees 2θ and 23.51±0.1 degrees 2θ.
 3. A crystalline compound according to claim 1, with an XRPD spectrum substantially as shown in FIG.
 1. 4. A crystalline compound according claim 2 characterized by a Thermo Gravimetric Analysis (TGA) curve showing an endothermic event at about 163° C.±2° C.
 5. A crystalline compound according to claim 2 characterized by a Differential Scanning Calorimetry (DSC) curve showing an endothermic event at about 163° C.±2° C.
 6. A crystalline compound according to claim 1 characterized by an XRPD spectrum comprising four or more peaks selected from peaks with 2θ angles of: 9.37±0.10 degrees 2θ, 10.34±0.10 degrees 2θ, 12.59±0.10 degrees 2θ, 13.17±0.10 degrees 2θ, 15.00±0.10 degrees 2θ, 15.63±0.10 degrees 2θ, 18.51±0.10 degrees 2θ, 19.10±0.10 degrees 2θ, 20.79±0.10 degrees 2θ and 23.93±0.10 degrees 2θ.
 7. A crystalline compound according to claim 1, with an XRPD spectrum substantially as shown in FIG.
 2. 8. A crystalline compound according to claim 6 characterized by a Thermo Gravimetric Analysis (TGA) curve showing an endothermic event at about 155° C.±2° C.
 9. A crystalline compound according to claim 6 characterized by a Differential Scanning Calorimetry (DSC) curve showing an endothermic event at about 180° C.±2° C.
 10. A crystalline compound according to claim 1 characterized by an XRPD spectrum comprising four or more peaks selected from peaks with 2θ angles of: 9.33±0.1 degrees 2θ, 10.73±0.1 degrees 2θ, 14.85±0.1 degrees 2θ, 15.29±0.1 degrees 2θ, 15.77±0.1 degrees 2θ, 16.16±0.1 degrees 2θ, 18.60±0.1 degrees 2θ, 20.12±0.1 degrees 2θ, 21.00±0.1 degrees 2θ and 23.22±0.1 degrees 2θ.
 11. A crystalline compound according to claim 1, with an XRPD spectrum substantially as shown in FIG. 3 or in FIG.
 20. 12. A crystalline compound according to claim 10 characterized by a Thermo Gravimetric Analysis (TGA) curve showing an endothermic event at about 149° C.±2° C.
 13. A crystalline compound according to claim 10 characterized by a Differential Scanning Calorimetry (DSC) curve showing an endothermic event at about 185° C.±2° C.
 14. A crystalline compound according to claim 1 characterized by an XRPD spectrum comprising four or more peaks selected from peaks with 2θ angles of: 6.7824±0.05 degrees 2θ, 15.4567±0.05 degrees 2θ, 16.3961±0.05 degrees 2θ, 17.1082±0.05 degrees 2θ, 20.0651±0.05 degrees 2θ, 20.6373±0.05 degrees 2θ, 23.2376±0.05 degrees 2θ, 23.6811±0.05 degrees 2θ, 26.1802±0.05 degrees 2θ and 32.4753±0.05 degrees 2θ.
 15. A crystalline compound according to claim 1, with an XRPD spectrum substantially as shown in FIG.
 25. 16. A crystalline compound according to claim 1 characterized by an XRPD spectrum comprising four or more peaks selected from peaks with 2θ angles of: 6.8269±0.05 degrees 2θ, 15.0475±0.05 degrees 2θ, 15.6848±0.05 degrees 2θ, 16.4735±0.05 degrees 2θ, 17.1773±0.05 degrees 2θ, 18.4488±0.05 degrees 2θ, 20.6999±0.05 degrees 2θ, 23.3436±0.05 degrees 2θ, 23.8843±0.05 degrees 2θ and 25.3818±0.05 degrees 2θ.
 17. A crystalline compound according to claim 1, with an XRPD spectrum substantially as shown in FIG.
 27. 18. A crystalline compound according to claim 1 characterized by an XRPD spectrum comprising four or more peaks selected from peaks with 2θ angles of: 12.7398±0.05 degrees 2θ, 15.3615±0.05 degrees 2θ, 15.9547±0.05 degrees 2θ, 16.4290±0.05 degrees 2θ, 18.1207±0.05 degrees 2θ, 20.4870 0.05 degrees 2θ, 22.8548±0.05 degrees 2θ, 23.2204±0.05 degrees 2θ, 27.0457±0.05 degrees 2θ, 27.6934±0.05 degrees 2θ and 32.4785±0.05 degrees 2θ.
 19. A crystalline compound according to claim 1, with an XRPD spectrum substantially as shown in FIG.
 29. 20. A crystalline compound according to claim 18 characterized by a Thermo Gravimetric Analysis (TGA) curve showing an endothermic event at about 160° C.
 21. A crystalline compound according to claim 18 characterized by a DSC profile showing an exothermic peak at approximately 184° C.
 22. A process for preparing a crystalline compound of formula (I):

the process comprising the steps of: forming a formulation by dissolving or suspending an amorphous compound of formula (I) in a solvent or solvent mixture; and crystallizing the compound of formula (I) from the formulation. 23-31. (canceled)
 32. A crystalline compound of formula (I) according to claim 1 wherein the compound comprises more than 90% of a single crystalline polymorph of the compound.
 33. A crystalline compound of formula (I) according to claim 1 having a chemical purity of at least 95 wt %.
 34. A pharmaceutical composition comprising a crystalline compound of formula (I) according to claim
 1. 35. A pharmaceutical composition according to claim 34 further comprising an antibiotic.
 36. (canceled)
 37. A method of treating a bacterial infection comprising administering to a patient in need thereof a therapeutically effective amount of the pharmaceutical composition according to claim
 34. 38. A method of treating a bacterial infection comprising co-administering to a patient in need thereof a therapeutically effective amount of the pharmaceutical composition according to claim 34 with a therapeutically effective amount of an antibiotic. 